In an operating network, multicast services can be carried on a multi-ring network constituted by traditional Synchronous Digital Hierarchy (SDH) Multiplex Section Protection (MSP) rings or Path Protection (PP) rings. If the rings in the ring network are relatively large, switching time of MSP may exceed 50 ms and up to 200 ms, or even more. The long switching time of MSP results in the black screen or mosaics on TV, and cannot satisfy the requirement that the recovery time of service protection should be less than 50 ms. Furthermore, a ring network cannot provide protection for a second fiber break failure. For a network that covers a broad area and has a high possibility of fiber break failures, it is desirable for the operator of the network to provide a service having a protection time less than 50 ms for both two fiber break failures. If the network has a low possibility of occurring failures and considering economic factors, a service that has a protection time less than 50 ms for the first failure and has a recovery time less than several hundreds milliseconds for the second failure is also desirable.
An ASON introduces a Control Plane (CP) between a Transport Plane (TP) and a Management Plane (MP), so that ASON has Automatic Neighbor Discovery Function, Automatic Link Discovery Function and Automatic Topology Discovery Function, and provides service with multiple types of protection and recovery such as Permanent 1+1 Protection, 1+1 Protection and Recovery, Dynamic Re-routing, and no protection. Presently, ASONs that provide connection services for various service levels of Point-to-Point service have come into commercial applications, but ASONs that support multicast service has not come into commercial applications. If a multicast service is split into a plurality of independent Point-to-Point services that cannot share the bandwidth, the bandwidth can be severely wasted although the requirement of various service levels is satisfied.
A solution is provided in the existing methods. According to the solution, multicast service is provided on a traditional SDH ring network, and routing and timeslots for the multicast service are configured by a network element cross-connect function or end to end connection management function in a network management system.
Such a solution cannot provide protection for a second fiber break failure, and the solution cannot provide protection of interconnection node failures in a single node interconnection ring either. For cross-ring service in a dual-node interconnection ring, though the solution can provide protection for a single node failure, service routing, service timeslot and service cross can only be configured manually. Both configuration and maintenance of the service are extremely complex. Furthermore, the ring network restricts the flexibility of network construction.
According to the existing methods, another solution is to provide a dynamic re-routing multicast service on ASON. However, dynamic re-routing services cannot satisfy the requirement that the recovery time of the first failure, even the second failure, shall be less than 50 ms.
Therefore, there is a need for a solution for providing multicast service with multiple types of protection and recovery, so as to address the above problems.